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        <td class="header">&nbsp;Create Stack</td>
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<h3>Create Stack Operator</h3>

<p>
    Create Stack is a component of <a href="../tutorials/coregistering_products.html">coregistration.</a>
    The <span style="font-style: italic;">Create Stack</span><em> </em>Operator
    allows&nbsp;collocating two spatially overlapping products. Collocating two
    products implies that the pixel values of one product (the <em>slave</em>)
    are resampled into the geographical raster of the other (the <em>master</em>).

</p><br>

<p>When two products are collocated, the band data of the slave product
    is resampled into the geographical raster of the master product.&nbsp;&nbsp;
    In order to establish a mapping between the samples in the master and the
    slave rasters, the geographical position of a master sample is used to find
    the corresponding sample in the slave raster. If there is no sample for a
    requested geographical position, the master sample is set to the no-data value
    which was defined for the slave band. The collocation algorithm requires accurate
    geopositioning information for both master and slave products. When necessary,
    accurate geopositioning information may be provided by <a href="../visat/GcpManagement.html">ground control
        points</a>. The metadata
    for the stack product is copied from the metadata of the master product.
</p><h4>Resampling Methods Supported</h4>&nbsp;&nbsp;&nbsp;The user may choose between three different resampling
methods:<br>
<ul>
    <li>None (For interferometric processing, no resampling should be used here)</li>
    <li><a href="../general/ResamplingMethods.html">Nearest
        Neighbour</a>,
    </li>
    <li><a href="../general/ResamplingMethods.html">Bilinear
        Interpolation</a>, and
    </li>
    <li><a href="../general/ResamplingMethods.html">Cubic
        Convolution</a>.
    </li>
</ul>
<h4>Output Extents</h4>&nbsp;&nbsp; User can select one of the following three extents for the collocated images:<br>
<ul>
    <li>Master: the master image extents (Master extents are always used with "None" resampling)</li>
    <li>Maximum: both the common coverage and the non overlapping areas</li>
    <li>Minimum: only the common coverage</li>
</ul>
<h4>Parameters Used</h4>&nbsp;&nbsp; The following parameters are used by this operator:
<ol>
    <li>Master Band: All bands (real or virtual) of the selected product. User can select
        one band (for real image) or two bands (i and q bands for complex image) as master
        band for co-registration.
    </li>
    <li>Slave Band: All bands (real or virtual) of the selected product. User can select
        one band (for real image) or two bands (i and q bands for complex image) as slave
        band for co-registration.
    </li>
    <li>Resampling Type: It specifies the resampling method.</li>
    <li>Output Extents: The output image extent.</li>
</ol>
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